1. Field of the Invention
The present invention generally pertains to methods of removing smoke and toxic compounds produced from fires, for general fire suppression, and fire retardancy. More particularly, methods according to the present invention involve the use of nanocrystalline materials, alone or in combination with other conventional materials, to achieve these purposes.
2. Description of the Prior Art
The hazards to human and animal life and health associated with fires, smoke, and toxic materials produced by fires are well known. Inhalation of toxic gases in smoke is the primary cause of fatalities in most fires. Fire is a complex, dynamic, physiochemical phenomenon and is a result of a rapid chemical reaction generating smoke, heat, flame and light. Each fire exhibits individual characteristics which depend on the types of burning materials and environmental conditions. Smoke is a complex of particular matter, as well as a variety of invisible combustion gases and vapors suspended in the fire atmosphere. Fire, smoke and the toxic compounds associated therewith can also cause poor visibility conditions thereby hampering the conduct of military and civilian ground operations (i.e., battlefield operations, search and rescue operations, aircraft operations, etc.).
Within the fire community it has long been an accepted fact that the health hazard from fire smoke is due mainly to its content of CO. Lately, this scenario has also come to include hydrogen cyanide (HCN). Isocyanates have also become the subject of focus as they are used for manufacturing polyurethanes and frequently used for manufacturing glues and lacquers. Isocyanates are known to induce asthma in people exposed to even relatively small amounts. NIOSH provide an IDLH of 2.5 ppm for 2,4-diisocyanate and 3.0 ppm for methyl isocyanate, for comparison, the IDLH given for HCN is 50 ppm and for CO 1200 ppm. Materials such as glass wool insulation, mineral wool insulation, and products utilizing nitrogen containing (urea based) binders and wood fibers have been found to release significant amounts of isocyanates (isocyanic acid and methyl isocyanate) when combusted.
In addition, smoke and toxic chemicals can be produced by a number of industrial processes. Newer environmental standards require reduction of the amounts of these materials from industrial flue gases prior to release into the atmosphere.
Conventional dry chemical systems for fire suppression have involved the use of pressurized containers including various dry compounds such as ammonium phosphate, ammonium sulfate, calcium carbonate, magnesium aluminosilicate, mono ammonium phosphate, sodium bicarbonate, potassium bicarbonate, and muscovite mica. However, these systems at best are only marginally effective at smoke removal and do not address the hazards presented by fire-produced toxic compounds.
Therefore, there is a real an unfulfilled need in the art for methods of smoke-clearing, fire suppression, flame retardancy and sorption of toxic chemicals produced by fires and industrial processes.